Derivative Financial Instruments (Details) (Non-Hedging Derivative Instruments, USD $)	3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2013 FSC	Sep. 30, 2013 FSC	Sep. 30, 2013 PrimeLending	Sep. 30, 2013 PrimeLending	Sep. 30, 2013 Commitments to purchase MBSs	Dec. 31, 2012 Commitments to purchase MBSs	Sep. 30, 2013 Commitments to sell MBSs	Dec. 31, 2012 Commitments to sell MBSs	Sep. 30, 2013 Interest rate lock commitments	Dec. 31, 2012 Interest rate lock commitments	Dec. 31, 2012 Interest rate swaps Cash Flow Hedges
Derivative financial instruments
Net gain (loss) due to changes in the fair value of the derivative instruments	$ 3,200,000	$ 8,800,000	$ (48,900,000)	$ (14,900,000)
Notional Amount					283,437,000	165,128,000	1,826,399,000	1,586,930,000	798,837,000	968,083,000	1,969,000
Estimated Fair Value					$ 7,443,000	$ 466,000	$ (29,290,000)	$ (1,025,000)	$ 26,440,000	$ 15,150,000	$ 25,000